TWI636079B - Optical film and manufacturing method thereof - Google Patents

Abstract

The present invention provides an optical film, which is an optical film composed of a hydrogenated block copolymer [2] obtained by hydrogenating all unsaturated bonds of the block copolymer [1], and the above-mentioned block copolymerization The substance [1] is two or more polymer blocks [A] having a repeating unit derived from an aromatic vinyl compound as a main component, and a repeating unit derived from a chain conjugated diene compound as a main component. When one or more types of polymer blocks [B] are used, and the weight fraction of all the polymer blocks [A] and [B] in the entire block copolymer is set to wA and wB, (wA: wB) is 40: 60 ~ 80: 20; the height from the apex of the adjacent mountain of the die line formed in the length direction of the diaphragm to the bottom of the valley is the diaphragm The whole surface is 100 nm or less, and the inclination of the die line on the surface of the film is 300 nm / mm or less. According to the present invention, an optical film with few surface defects is provided.

Description

Optical film and manufacturing method thereof

The present invention relates to an optical film composed of a block copolymer hydride, which is useful as a protective film for a polarizing plate, and the like. More specifically, the present invention relates to a film having fewer surface defects and less Excellent optical film.

An aromatic vinyl compound polymer hydrogenated product obtained by hydrogenating an aromatic ring of an aromatic vinyl compound polymer, and a polymer block and a source containing a repeating unit derived from an aromatic vinyl compound as a main component are known. Aromatic rings of block copolymers composed of polymer blocks of repeating units of a chain-like conjugated diene compound, hydrogenated block copolymers derived from hydrogenation of double bonds derived from diene, and the like can be used Optical films such as polarizing films and retardation films can be stretched by extrusion to give a desired retardation (Patent Documents 3 to 6).

On the other hand, a film made of a thermoplastic resin used in a device that operates polarized light such as a liquid crystal display device is required to be optically transparent, and the phase difference in the plane direction and thickness direction to be small and not change The lens effect caused by the unevenness on the surface of the diaphragm is likely to cause image distortion.

Therefore, the uniformity of the thickness of the film is highly demanded in the application of the optical film, and the optical film can be obtained with excellent thickness uniformity. From the viewpoint of a diaphragm, a solution casting method has previously been used for manufacturing.

In recent years, the solution casting method has been pointed out due to the environmental pollution caused by the solvent, the low yield, etc., and the melt extrusion method is gradually widely used. However, regarding the melt extrusion method, in addition to the thickness of the film formed by the film being easily changed, there is also a disadvantage that a die line is easily generated in the direction of film extrusion.

The die line is made of a molten resin extruded from an extrusion die. A die line attached to a wall surface of an extrusion die and the adhesion marks appear as linear marks, and a die line formed by a resin mark adhered to a die lip of the extrusion die. These die lines are composed of mountains and valleys having an unevenness of about 0.1 to 0.5 μm and a width of about 50 to 500 μm.

In the optical film, the die line is a cause of an optical signal error or an adverse effect of a die line pattern reflected on a display or the like. Therefore, when the film is extruded, the temperature of the molten resin is adjusted, the melting viscosity is selected, the air gap between the cooling roller and the extrusion die, and the molten resin film after the molten resin film contacts the cooling roller. Attempts to apply voltage to the chip. In addition, the die lip portion of the extrusion die is subjected to a gold-plating treatment such as grinding treatment or chrome-plating.

However, these methods do not sufficiently prevent the die line, which causes the die line to gradually increase during continuous production, and causes various problems such as the production surface and the stability of product characteristics.

Therefore, various studies have been conducted.

For example, Patent Document 1 proposes a transparent resin sheet characterized by being composed of a cyclic olefin-based thermoplastic resin and forming a smooth surface with a surface roughness of 0.01 μm or less on at least one surface, and a thickness of 0.05 to 3 mm. And the residual phase difference is 20 nm. Also, in this document, it is used as a method for manufacturing the sheet. The method describes that a cyclic olefin-based thermoplastic resin in a molten state is pressed from a T-die installed in an extruder, and the ring is pressed by a metal cooling roller and a metal cooling belt. The olefin-based thermoplastic resin is pressure-bonded to the cooling roller or the cooling belt, and then the cyclic olefin-based thermoplastic resin is cooled from the cooling roller or the cooling at a temperature equal to or lower than the glass transition temperature of the cyclic olefin-based thermoplastic resin. Peel with tape.

Also, Patent Document 2 proposes a cyclic olefin resin A method for manufacturing an extruded article (sheet or film shape) is characterized in that the cyclic olefin resin is melted and the cyclic olefin resin in a molten state is passed through a mold having a mold lip portion having a peel strength of 75N or less. Extruded and shaped cyclic olefin resin. In addition, this document describes that the method can be suitably used for optical applications because it has very excellent surface smoothness when using this method.

Furthermore, Patent Document 3 discloses a method for manufacturing an optical film. A method for manufacturing an amorphous thermoplastic resin having an alicyclic structure by an extruder, extruding the extruded sheet into a sheet shape, and extruding the extruded sheet-like amorphous thermoplastic resin. The step of forming and winding in close contact with at least one cooling drum, wherein the average value of the surface roughness Ra by using the extrusion die lip is 0.05 μm or less, and on the surface of the entire width of the extrusion die lip The distribution range of the roughness Ra is ± 0.025 μm or less of the aforementioned average value. It can be obtained that the height from the vertex of the die line adjacent to the bottom of the valley to the bottom of the valley is 100 nm or less, and the film The inclination of the die line on the surface of the sheet is an optical film having an entire surface of the film of 300 nm / mm or less.

On the other hand, in Patent Documents 4 and 6, there is disclosed a method by which A polymer block derived from an aromatic vinyl compound and a conjugated diene A block copolymer hydride obtained by hydrogenating both polymer blocks of a compound can obtain an optical compensation film and an optical film with a small phase difference. Compared to thermoplastic resins with alicyclic structures synthesized from cyclic olefins, block copolymer hydrides are easier to obtain as aromatic vinyl compounds and conjugated dienes as raw materials, so they are supplied on a larger scale. It is relatively easy to use, and a practical system using the optical film is expected.

Prior art literature Patent literature

[Patent Document 1] Japanese Patent Laid-Open No. 2000-219752

[Patent Document 2] Japanese Patent Laid-Open No. 2000-280315

[Patent Document 3] Japanese Patent Laid-Open No. 2005-128360

[Patent Document 4] Japanese Patent Laid-Open No. 2003-114329

[Patent Document 5] International Publication No. WO2009 / 067290 (US2010 / 290117A1)

[Patent Document 6] International Publication No. WO2009 / 137278 (US2011 / 038045A1)

In recent years, with the high definition and high brightness of liquid crystal display devices, when a display device having a high-brightness light source uses an optical film obtained in accordance with the method described in these publications, it can be visually inspected. Obviously, it is observed that the lines originating from the die line are displayed on the screen as bright or dim light, or there is a problem of light leakage, and further improvement is required.

In this case, compared with the thermoplastic resins having an alicyclic structure synthesized from cyclic olefins disclosed in Patent Documents 2, 3, etc., the applicant of this case found that the resins disclosed in Patent Documents 4, 6, etc. A hydrogenated block copolymer obtained by hydrogenating both polymer blocks derived from an aromatic vinyl compound and polymer blocks derived from a conjugated diene compound. The mold lip has less adhesion due to oxidative degradation.

However, it may not be possible to reduce the die line.

Therefore, an object of the present invention is to provide an optical film which uses a block copolymer hydride which is easily supplied on a large scale in industry, and is particularly used in a display device having a high-definition and high-brightness light source. Compared with the former, there are fewer surface defects and it is impossible to confirm the light and dark lines due to the die line, and there is no light leakage.

In order to achieve the above-mentioned object, the inventors have intensively studied and found that by using a specific extrusion die when melt-extruding a film of a specific block copolymer hydride, The pellets of the block copolymer hydride are heat-treated in a specific temperature range for a specific time or longer to achieve the above-mentioned object and completed the present invention.

Thus, according to the present invention, it is possible to provide the following (1) optical film, (2) polarizing plate protective film, (3) retardation film, and (4) optical film manufacturing method.

(1) An optical film, which is an optical film composed of a hydrogenated block copolymer [2] obtained by hydrogenating all unsaturated bonds of the block copolymer [1], and the block copolymer described above [1] Based on repeating units derived from aromatic vinyl compounds A polymer block [A] of at least two kinds of main components and a polymer block [B] of repeating units derived from a chain-like conjugated diene compound as the main component. When the weight fraction of block [A] in the entire block copolymer is set to wA and the weight fraction of all polymer blocks [B] in the entire block copolymer is set to wB, The ratio of wA to wB (wA: wB) is 40:60 to 80:20, and is characterized by counting from the vertex of the adjacent mountain of the die line formed in the length direction of the diaphragm to the bottom of the valley. The height is 100 nm or less across the entire surface of the film, and the inclination of the die line on the surface of the film represented by Formula 1 is 300 nm / mm or less across the entire surface of the film.

[Number 1] Slope (nm / mm) = (height from the apex of the adjacent mountain to the bottom of the valley) / (width from the apex of the adjacent mountain to the bottom of the valley) ‧ ‧ formula 1

(2) A polarizing plate protective film including the optical film according to (1).

(3) A retardation film obtained by extending the optical film according to the above (1).

(4) A method for producing a film for optics, which comprises melting a block copolymer hydride [2] by an extruder and extruding it into a sheet shape from an extrusion die installed in the extruder; and The step of forming the extruded sheet-like block copolymer hydride [2] in close contact with at least one cooling drum and forming and winding it is characterized by using an average of the surface roughness Ra of the lip of the extrusion die. An extrusion die with a value of 0.05 μm or less and a surface roughness Ra in the entire width of the lip of the extrusion die is ± 0.025 μm or less of the aforementioned average value, and used at a temperature of 50 to 120 ° C. for more than 2 hours Pellets of block copolymer hydride [2].

According to the present invention, it is possible to provide an optical film that has fewer surface defects than the former and is used in a display device having a high-brightness light source. The light and dark lines due to the die line cannot be confirmed, and there is no light leakage. sheet.

1‧‧‧ baseline

2‧‧‧ Peak of the mountain

The bottom of the valley

4‧‧‧ Distance from the peak of the mountain to the bottom of the valley

5, 6‧‧‧ line

7‧‧‧ Height from the peak of the mountain to the bottom of the valley

FIG. 1 is an enlarged portion of a die line of the optical film of the present invention.

Forms used to implement the invention

The optical film of the present invention is an optical film composed of a hydrogenated block copolymer [2] obtained by hydrogenating all unsaturated bonds of the block copolymer [1], and the block copolymer [1] ] Is a polymer block [A] having at least two kinds of repeating units derived from an aromatic vinyl compound as a main component and at least one kind of repeating units derived from a chain conjugated diene compound as a main component The polymer block [B] is composed, and the weight fraction of the entire polymer block [A] in the entire block copolymer is set to wA, and the entire polymer block [B] is included in the entire block copolymer. When the occupied weight fraction is set to wB, the ratio of wA to wB (wA: wB) is 40:60 to 80:20.

Block copolymer [1]

The precursor of the block copolymer hydride [2] of the present invention, that is, the block copolymer [1], contains at least two polymer blocks [A] and at least one polymer block [B].

The polymer block [A] is a component having a structural unit derived from an aromatic vinyl compound as a main component. Aromatic vinyl in polymer block [A] The content of the structural unit of the compound is usually 90% by weight or more, preferably 95% by weight or more, and more preferably 99% by weight or more.

The polymer block [A] can contain a structural unit derived from a chain conjugated diene and / or a structural unit derived from another vinyl compound as a component other than a structural unit derived from an aromatic vinyl compound. . Its content is usually 10% by weight or less, preferably 5% by weight or less, and more preferably 1% by weight or less. When the content of the structural unit derived from the aromatic vinyl compound in the polymer block [A] is too small, the heat resistance of the optical film of the present invention may be reduced.

The plural polymer blocks [A] may be the same as or different from each other as long as they satisfy the above range.

The polymer block [B] has a structural unit derived from a chain conjugated diene compound as a main component. The content of the structural unit derived from the chain conjugated diene compound in the polymer block [B] is usually 90% by weight or more, preferably 95% by weight or more, and more preferably 99% by weight or more. When the structural unit derived from the chain conjugated diene compound is in the above range, the birefringence manifestation when the optical film of the present invention is extended is good, and the film can also be given flexibility.

In addition, the polymer block [B] can contain a structural unit derived from an aromatic vinyl compound and / or a structural unit derived from another vinyl compound as a structural unit other than a chain conjugated diene compound. ingredient. Its content is usually 10% by weight or less, preferably 5% by weight or less, and more preferably 1% by weight or less. When the content of the structural unit derived from the aromatic vinyl compound in the polymer block [B] is increased, the birefringence visibility of the film may be reduced. When there are a plurality of types of polymer blocks [B], the polymer blocks [B] may be the same as or different from each other as long as they satisfy the above range.

Examples of the aromatic vinyl compound include styrene; α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, and 2,4-diisopropylbenzene Alkyl substituted styrenes such as ethylene, 2,4-dimethylstyrene, 4-tert-butylstyrene, 5-tert-butyl-2-methylstyrene; 4-chlorostyrene, 2, Halogen-substituted styrenes such as 4-dichlorostyrene, 4-fluorostyrene, etc .; Aryl-substituted styrenes such as 4-phenylstyrene; 4-methoxystyrene, 3,5-dimethoxybenzene Alkoxy-substituted styrene such as ethylene; in terms of hygroscopicity, it is better to use styrene, alkyl-substituted styrene, etc. which do not contain polar groups, and from the viewpoint of industrial availability, styrene is used Extraordinary.

Specific examples of the chain conjugated diene-based compound include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. In terms of hygroscopicity, diene and the like are preferably those which do not contain a polar group, and in terms of industrial availability, 1,3-butadiene and isoprene are particularly preferred.

Examples of other vinyl compounds include chain vinyl compounds, cyclic vinyl compounds, and the like. These vinyl compounds may contain a vinyl compound having a nitrile group, an alkoxycarbonyl group, a hydroxycarbonyl group, or a halogen atom as a substituent, and / or an unsaturated cyclic acid anhydride or an unsaturated sulfonimine compound. As other vinyl compounds, in terms of hygroscopicity, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-nonene are used. Chain olefins such as 1-decene, 1-dodecene, 1-icosene, 4-methyl-1-pentene, 4,6-dimethyl-1-heptene, etc .; vinylcyclohexene Cyclic olefins, such as alkanes, are preferred if they do not contain a polar group, chain olefins are preferred, and ethylene and propylene are particularly preferred.

The number of polymer blocks [A] in the block copolymer [1] is usually 5 or less, preferably 4 or less, and more preferably 3 or less. Polymer block When there are a plurality of [A] and / or polymer blocks [B], the weight average molecular weight of the polymer block having the largest and smallest weight average molecular weight in the polymer block [A] is each set as Mw (A1) and Mw (A2), and the weight average molecular weight of the polymer block [B] having the largest and smallest weight average molecular weights is respectively Mw (B1) and Mw (B2 ), The ratio of Mw (A1) to Mw (A2) (Mw (A1) / Mw (A2)) and the ratio of Mw (B1) to Mw (B2) (Mw (B1) / Mw (B2)) are Each is 2.0 or less, preferably 1.5 or less, and more preferably 1.2 or less.

The block morphology of the block copolymer [1] may be a chain block, and It may be a radial block, and a chain block is preferable because it has excellent mechanical strength. The best morphology of the block copolymer [1] is that the polymer block [A] is bonded to both ends of the polymer block [B], and the third block is represented by [A]-[B]-[A]. A segment copolymer, and a polymer block [B] is bonded to both ends of the polymer block [A], and further, a polymer block [B] is bonded to the other end of the two polymer blocks [B] A] is a pentablock copolymer represented by [A]-[B]-[A]-[B]-[A].

All polymer blocks [A] in block copolymer [A] When the weight fraction occupied by the entire polymer is set to wA and the weight fraction occupied by all the polymer blocks [B] in the entire block copolymer is set to wB, the ratio of wA to wB (wA: wB) is 40: 60 ~ 80: 20, preferably 50: 50 ~ 75: 25, more preferably 60: 40 ~ 70: 30. When the ratio of wA is too high, although the heat resistance of the modified block copolymer hydride [3] used in the present invention becomes high, the flexibility is low and the optical film becomes easily cracked on the cutting surface. . On the other hand, when the ratio of wA is too low, the heat resistance is lowered and the film is stretched and contracted immediately, and the phase difference may not be maintained.

The molecular weight of the block copolymer [1] is based on tetrahydrofuran (THF) The polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) as a solvent is usually 30,000 to 200,000, preferably 40,000 to 150,000, and more preferably 50,000 to 100,000. The molecular weight distribution (Mw / Mn) of the block copolymer [1] is preferably 3 or less, more preferably 2 or less, and particularly preferably 1.5 or less.

For the block copolymer [1], for example, living anionic polymerization can be used. It is manufactured by a conventional manufacturing method. More specifically, the monomer mixture (a) containing an aromatic vinyl compound as a main component and the monomer mixture (b) containing a chain conjugated diene compound as a main component may be alternately polymerized. Method: A monomer mixture (a) containing a main component of an aromatic vinyl compound and a monomer mixture (b) containing a chain conjugated diene compound as a main component are polymerized in order. A method for coupling the ends of the polymer block [B] with the mixture, and the like.

2. Block copolymer hydride [2]

The hydrogenated block copolymer [2] of the present invention is obtained by hydrogenating carbon-carbon unsaturated bonds in the main chain and side chains of the block copolymer [1] and carbon-carbon unsaturated bonds in the aromatic ring. . The hydrogenation rate is usually 90% or more, preferably 97% or more, and more preferably 99% or more. The higher the hydrogenation rate, the better the weatherability and heat resistance of the formed body. The hydrogenation rate of the block copolymer hydride [2] can be determined by ¹ H-NMR measurement.

The hydrogenation method of the unsaturated bond, the form of the hydrogenation reaction, and the like are not particularly limited, and they may be performed according to a conventional method. In terms of improving the hydrogenation rate, a hydrogenation method with less polymer chain cleavage reaction is preferred. As this hydrogenation Examples of the method include methods described in International Publication No. WO2011 / 096389, International Publication No. WO2012 / 043708, and the like.

The block copolymer hydride [2] obtained by the above method, After removing the hydrogenation catalyst and / or the polymerization catalyst from the reaction solution containing the block copolymer hydride [2], it can be recovered from the reaction solution. The morphology of the recovered block copolymer hydride [2] is not limited, and usually it can be formed into a pellet shape to provide subsequent film forming processing.

The molecular weight of the block copolymer hydride [2] is based on tetrahydrofuran The polystyrene-equivalent weight average molecular weight (Mw) measured by GPC using THF as a solvent is usually 35,000 to 200,000, preferably 40,000 to 150,000, and more preferably 45,000 to 100,000. The molecular weight distribution (Mw / Mn) of the hydrogenated block copolymer [2] is preferably 3 or less, more preferably 2 or less, and particularly preferably 1.5 or less. When Mw and Mw / Mn are set to the above ranges, the mechanical strength and heat resistance of the formed film are improved.

The hydrogenated block copolymer [2] used in the present invention may contain other formulation agents. The formulation is not particularly limited, and examples include layered crystalline compounds; inorganic fine particles; antioxidants, heat stabilizers, light stabilizers, weather-resistant stabilizers, ultraviolet absorbers, near-infrared absorbers, and stabilizers; slip agents , Plasticizers and other resin modifiers; dyes, pigments and other coloring agents; antistatic agents. These formulations can be used alone or in combination of two or more. The blending amount can be appropriately selected within a range that does not impair the object of the present invention.

When the block copolymer hydride [2] is melt-extruded and formed into a film, it is effective to add an antioxidant in order to prevent the resin oxidative degradation substance from adhering to the die lip of the extrusion die. Examples of the antioxidant include phenol-based antioxidants and phosphorus-based antioxidants. Antioxidants, sulfur-based antioxidants, and the like are preferably phenol-based antioxidants, especially alkyl-substituted phenol-based antioxidants. The blending amount of the antioxidant can be appropriately selected within a range that does not impair the object of the present invention, and is generally 0.005 to 1 part by weight, preferably 0.01 to 0.5 with respect to 100 parts by weight of the block copolymer hydride [2]. Parts by weight.

3. Optical film

The optical film of the present invention has a die line formed in the longitudinal direction of the film, the height from the apex of the adjacent mountain to the bottom of the valley is 100 nm or less across the entire surface of the film. The inclination of the die line on the surface of the diaphragm shown is that the entire surface of the diaphragm is 300 nm / mm or less.

[Number 2] Slope (nm / mm) = (height from the apex of the adjacent mountain to the bottom of the valley) / (width from the apex of the adjacent mountain to the bottom of the valley). ． ． Formula 1

The so-called length direction refers to the flow direction of the extruded film. The so-called "height of the die line formed in the longitudinal direction of the diaphragm from the apex of the adjacent mountain to the bottom of the valley is 100nm or less across the whole of the diaphragm" means that the height of the die line is all It is 100 nm or less. In addition, "the inclination of the die line on the surface of the diaphragm is 300 nm / mm or less across the entire surface of the diaphragm" means that the inclination of the die line is all 300 nm / mm or less.

In the optical film of the present invention, the height is preferably 50 nm or less, more preferably 30 nm or less, and the tilt system is preferably 100 nm / mm or less, and more preferably 50 nm / mm or less. The height and inclination of the die line from the apex of the adjacent mountain to the bottom of the valley are within the above range, and even when incorporated in a liquid crystal display unit with a high-brightness backlight module, it can become a no-light spot. And has a good display state.

The height and inclination of the die line from the apex of the adjacent mountain to the bottom of the valley can be analyzed by using a three-dimensional surface structure analysis microscope to scan the uneven surface of the diaphragm surface at a constant speed to generate interference fringes. To measure.

When measuring the height and inclination of the die line from the apex of the adjacent mountain to the bottom of the valley, the bottom point of the adjacent valley and the base of the peak of the mountain are different, as shown in Figure 1. Draw base line 1 from the top of the mountain or from the intersection of the bottom point 3 of the valley and the line perpendicular to the base line 1 and the intersection point of the base line 1 from the top of the mountain to the bottom of the valley Distance 4. In addition, the height is drawn through the apex 2 of the mountain or the bottom point 3 of the valley and parallel to the baseline, lines 5 and 6, and the shortest distance from line 5 to line 6 is set to height 7.

In the optical film of the present invention, the width 4 of the die line formed in the longitudinal direction of the film from the apex of the adjacent mountain to the bottom of the valley is preferably 500 μm or more, and more preferably 1000 μm or more. .

The thickness of the optical film of the present invention is usually 20 to 300 μm, and preferably 30 to 200 μm. The thickness variation of the diaphragm is preferably within 3% of the above thickness, and more preferably within 2.5%. By making the thickness variation of the film into the above range, it is possible to reduce color unevenness when the optical film of the present invention is incorporated in a liquid crystal display device.

4. Manufacturing method of optical film

The method for producing an optical film of the present invention comprises melting a block copolymer hydride [2] by an extruder, extruding the extruder from the extrusion die installed in the extruder into a sheet shape, and Extruded flaky block copolymer hydride [2] Forming and winding in close contact with at least one cooling drum.

The manufacturing method of the optical film of the present invention is characterized by: An extrusion die having an average value of the surface roughness Ra of the extrusion die lip of 0.05 μm or less and a distribution range of the surface roughness Ra across the entire width of the extrusion die lip is ± 0.025 μm or less of the aforementioned average value.

In the extrusion die used in the method for producing an optical film of the present invention, it is preferable that the average value of the surface roughness Ra of the extrusion die lip is 0.01 μm or less and the entire width of the extrusion die lip The distribution range of the surface roughness Ra is ± 0.005 μm or less of the aforementioned average value. The surface roughness Ra and its distribution system can use a non-contact three-dimensional surface shape. Roughness measuring machine. When the average value of the surface roughness Ra of the extrusion die lip is more than 0.05 μm, it is easy to generate an unacceptable die line due to the extrusion die.

In the method for producing an optical film of the present invention, The pellets of the polymer hydride [2] are used before the material is melt-extruded by an extruder, usually at 50 to 120 ° C, preferably 60 to 115 ° C, and preferably 70 to 110 ° C. It is preferably kept at a temperature of 2 hours or more and 48 hours or less. By heating the pellets of the block copolymer hydride [2] under the above conditions, it is possible to reduce the amount of dissolved air in the pellets and thereby suppress the occurrence of die lines. When the temperature and time of the heat treatment are lower than the above range, the amount of dissolved air is small and die line formation cannot be sufficiently suppressed, and when the temperature of the heat treatment is greater than the above range, the pellet of the block copolymer hydride [2] The granules are liable to stick together and may not provide extrusion molding. When the heat treatment time is longer than the above range, the color tone may be deteriorated.

The amount of dissolved air removed by heat treatment is usually 100 ppm or more, preferably 150 ppm or more. The amount of dissolved air discharged by heating the pellets can be measured from the weight reduction of the pellets before and after the heat treatment. The amount of dissolved air discharged from the pellets can also be measured using a Toepler pump.

After reducing the amount of dissolved air by heat treatment, cool at room temperature However, since the air is reabsorbed and restored to its original state even in an environment where moisture is isolated, the pellets after the heat treatment must be supplied to the melt extrusion step while maintaining the heated state, or after cooling Then, the air is supplied to the melt extrusion step before absorbing air again and returning to the original state. After cooling, it is usually preferably supplied to the melt extrusion step within 1 hour, preferably within 0.5 hour.

In the manufacturing method of the present invention, in an extruder having a T-die The melting temperature of the block copolymer hydride [2] is generally 70 to 160 ° C higher than the glass transition temperature of the block copolymer hydride [2], and is set to be 90 to higher than the glass transition temperature. A temperature of 140 ° C is preferred. The glass transition temperature of the block copolymer hydride [2] can be determined as a peak top value of tan δ in the viscoelastic spectrum. When the melting temperature of the extruder is too low, the resin may have insufficient fluidity. Conversely, when the melting temperature is too high, the resin may be decomposed and the molecular weight may be lowered.

As a sheet-like block extruded from the opening of an extrusion die The method for adhering the polymer hydride [2] to the cooling drum is not particularly limited, and examples thereof include a pneumatic doctor method, a vacuum box method, and an electrostatic adhesion method. The number of cooling drums is not particularly limited, but is usually two or more. In addition, examples of the arrangement method of the cooling drum include a linear type, a Z type, and an L type, but they are not particularly limited. In addition, a sheet-like block extruded from an opening of an extrusion die The manner in which the copolymer hydride [2] reaches the cooling drum is not particularly limited.

In the present invention, the extruded flaky block copolymer hydride [2] The tightness of the cooling drum changes according to the temperature of the cooling drum. When the temperature of the cooling drum is increased, although the adhesion is improved, if the temperature is increased too much, the sheet-like block copolymer hydride [2] may not be peeled off from the cooling drum and may cause a defect of being wound around the drum. . Therefore, when the block copolymer hydride [2] is usually set to Tg (° C), the temperature of the cooling drum is usually set to (Tg + 10) ° C or lower, and (Tg-80) ° C to (Tg-5) The range of) ° C is preferable, and the range of (Tg-60) ° C to (Tg-10) ° C is more preferable. By setting the temperature of the cooling drum to such a temperature range, defects such as sliding and scratches can be prevented.

In the present invention, the block copolymer hydride [2] is melted in an extruder. It is preferable that the molten block copolymer hydride [2] be passed through a gear pump and a filter before being extruded from an extrusion die installed in the extruder. By using a gear pump, it is possible to improve the uniformity of the extrusion amount of the resin and reduce the thickness unevenness. In addition, by using a filter, foreign matter in the resin can be removed to obtain a defect-free optical film having excellent appearance.

The optical film of the present invention can be used in a liquid crystal display device. Examples of components used in display devices such as polarizing plate protective films, retardation films, brightness enhancement films, transparent conductive films, substrates for touch panels, liquid crystal substrates, light scattering sheets, and thin sheets. Especially suitable for polarizing plate protective film and retardation film.

5. Polarizer protective film

The optical film of the present invention can be used as a polarizing plate protective film. When used as a polarizing plate protective film, the retardation Re in the film surface is 10 nm. The following is preferred, and 3 nm or less is preferred. When the phase difference is 10 nm or less, color unevenness when the liquid crystal display unit is incorporated can be suppressed. In a large-screen liquid crystal display device, the color does not tend to be particularly conspicuous, but the polarizing plate protective film of the present invention is suitable even for such a large-screen display device. The retardation Re in the diaphragm surface can be determined by using Re = (Nx-Ny) × d when the main refractive index in the diaphragm surface is Nx and Ny and the thickness of the diaphragm is d. The retardation Re in the diaphragm surface can also be measured using a commercially available automatic birefringence meter.

When the optical film of the present invention is used as a protective film for a polarizing plate, it is laminated on one or both sides of the polarizing plate through an appropriate adhesive. The polarizing plate system can be obtained by subjecting a polyvinyl alcohol-based film to doping with iodine or the like, followed by stretching. As the adhesive layer, an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyether, a synthetic rubber, or a block copolymer hydride [2] used in the present invention can be used to introduce an alkane. An appropriate polymer such as a modified block copolymer made of an oxysilyl group is used as an adhesive or an adhesive for the matrix polymer.

6. Phase difference diaphragm

The optical film system of the present invention can be used as a retardation film. When used as a retardation film, the optical film of the present invention can be stretched and used to provide a desired retardation. Examples of the stretching method include a method of uniaxial stretching in the longitudinal direction by utilizing the difference in the peripheral speed on the roll side during melt extrusion, and a method of uniaxial stretching in the transverse direction by using a wide stretcher. ; While expanding the interval of the fixed clips for longitudinal extension, and simultaneous biaxial extension by extending the angle of the guide rails; and the longitudinal extension by utilizing the difference in the peripheral speed between the rollers, the clamps hold it Both ends and use The widening stretcher performs a biaxial stretching method such as a sequential biaxial stretching method such as a lateral stretching.

The temperature at the time of the stretching treatment is usually a block copolymerization. When the glass transition temperature of the object [2] is set to Tg, it is preferably between (Tg-40 ° C) and (Tg + 30 ° C), and more preferably (Tg-30 ° C) to (Tg + 10 ° C). range. The stretching ratio is usually 1.01 to 30 times, preferably 1.05 to 10 times, and more preferably 1.1 to 5 times.

Examples of the retardation film of the present invention include a predetermined wave Long, supplying a 1/2 wavelength plate with a phase difference of 1/2 wavelength; supplying a 1/4 wavelength plate with a phase difference of 1/4 wavelength relative to a predetermined wavelength; combining the aforementioned 1/2 wavelength plate and 1/4 wavelength plate Wide-area quarter-wave plate bonded at a specific angle; positive retarder (a retardation element with a positive phase difference in the direction perpendicular to the element surface), negative retarder (having a negative in the direction perpendicular to the element surface) Phase difference element). The thickness of the retardation film of the present invention is usually 30 to 200 μm.

In the retardation film of the present invention, a plurality of retardation films may be used. The sheets are laminated so that the respective late phase axes intersect at a predetermined angle. For lamination, a conventional lamination method may be used. An adhesive or the like can also be used during lamination.

Examples

Hereinafter, the present invention will be described in more detail while showing examples. However, the present invention is not limited to the following examples. In addition, parts and% are weight basis as long as it is not specifically notified in advance.

The evaluation in this example was performed using the following method.

(1) Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)

The molecular weight of block copolymers and block copolymer hydrides The GPC of furan as an eluent was measured at 38 ° C. as a standard polystyrene conversion value and determined. As a measuring device, "HLC8020 GPC" manufactured by TOSOH Corporation was used.

(2) hydrogenation rate

The hydrogenation rates of the main chain, side chain, and aromatic ring of the block copolymer hydride [2] are calculated by measuring a ¹ H-NMR spectrum.

(3) Glass transition temperature

The block copolymer hydride was press-molded to prepare a test piece having a length of 20 mm, a width of 4 mm, and a thickness of 1 mm. Based on the JIS-K7244-4 method, a loss elastic modulus measuring device (manufactured by Seiko Instruments, product name "DMS6100J) In the range of -100 ° C to 150 ° C, the viscoelastic spectrum was measured at a vibration frequency of 10 Hz and a heating rate of 5 ° C / min, and the glass transition temperature was determined from the peak top temperature of the high temperature side of the loss coefficient tan δ.

(4) Surface roughness Ra of the lip of the extrusion die and its distribution

Use non-contact 3D surface shapes. Roughness measuring machine (manufactured by Zygo, product name "New View5000") and measured. The measurement was performed at 50 mm intervals across the full width of the extrusion die lip. The arithmetic mean of the measured values of Ra is set as a representative value, and the difference between each measured value and the arithmetic mean is set as a distribution of Ra.

(5) Film thickness (standard film thickness, uneven film thickness)

The diaphragm was cut every 100 mm in the length direction, and 10 pieces of the cut diaphragm were cut with a contact-type diaphragm thickness meter (manufactured by Meissan Corporation, product name "RC-101") in the width direction of the diaphragm 毎 0.48 mm The measurement was performed, and the arithmetic mean value of the measured values was set as the reference film thickness T (μm).

The film thickness unevenness refers to the maximum value among the film thicknesses measured above. TMAX (μm) is calculated from the following formula by setting the minimum value to TMIN (μm).

[Number 3] Uneven film thickness (%) = (TMAX-TMIN) / T × 100

(6) The height and inclination of the die line of the diaphragm from the apex of the adjacent mountain to the bottom of the valley

When the film is irradiated with light and the transmitted light is reflected on the screen, the position (die line) where the streaks of bright or dim light can be seen on the screen over the full width is observed. The film of the die line portion was cut to a size of about 3 cm square, and the surfaces of both sides of the film were observed using a three-dimensional surface structure analysis microscope (manufactured by Zygo). The film was measured by generating uneven dry streaks on the film.

(7) Light leakage

Each of the two blank (non-stretched) film sheets was stretched in the longitudinal direction (the stretching temperature was 132 ° C. and the stretching ratio was 2 times) to obtain a stretched film sheet. Laminates are manufactured. The laminated body was sandwiched between the polarizing plates such that the extension axis of each of the extending films was 45 degrees to the transmission axis of the polarizing plate. Next, light is transmitted from the backlight through the laminated body sandwiching the polarizing plate, and an illuminance meter (produced by Yokogawa METER & INSTRUMENTS, product name "51001") is disposed at a distance of 30 mm from the polarizing plate in the line direction. And the illuminance was measured. Set "light leakage" when the illuminance is 300 lux or more, and "light leakage" when the illuminance is less than 300 lux. In addition, the backlight panel is a person using 5,000 lux and 10,000 lux.

[Reference Example 1] Block copolymer hydride [2] -1 (Synthesis of block copolymer [1] -1)

In a reactor equipped with a stirring device sufficiently substituted with nitrogen inside, 550 parts of dehydrated cyclohexane, 30.0 parts of dehydrated styrene, and 0.475 parts of n-dibutyl ether were added, and n-butyllithium was added while stirring at 60 ° C ( 15% cyclohexane solution) 0.61 parts to start polymerization. It was made to react at 60 degreeC for 60 minutes, stirring. At this point measured using a gas chromatograph, the polymerization conversion rate was 99.5%.

Next, 40.0 parts of dehydrated isoprene was added, and stirring was continued at the same temperature for 30 minutes. The polymerization conversion rate at this point was 99.5%.

Subsequently, 30.0 parts of dehydrated styrene was further added and stirred at 60 ° C for 60 minutes. The polymerization conversion at this point was about 100%.

Here, 0.5 part of isopropyl alcohol was added to stop the reaction. The weight average molecular weight (Mw) of the obtained block copolymer [1] -1 was 80,400, the molecular weight distribution (Mw / Mn) was 1.03, and wA: wB = 60: 40.

(Synthesis of block copolymer hydride [2] -1)

Next, the polymer solution was transferred to a pressure-resistant reactor equipped with a stirring device, and 3.0 parts of diatomite-supported nickel catalyst (manufactured by SUD Chemie Catalyst Co., Ltd., product name "T-8400RL") was added as a hydrogenation catalyst. And 100 parts of dehydrated cyclohexane and mixed. The inside of the reactor was replaced with hydrogen, and hydrogen was supplied while stirring the solution, and a hydrogenation reaction was performed at a temperature of 190 ° C and a pressure of 4.5 MPa for 6 hours. The weight average molecular weight (Mw) of the hydrogenated block copolymer [2] -1 after the hydrogenation reaction was 81,200, and the molecular weight distribution (Mw / Mn) was 1.04.

After the completion of the hydrogenation reaction, the reaction solution was filtered to remove the hydrogenation catalyst, and then a phenolic antioxidant, namely neopentyl tetraol was added. 1.0 part of xylene solution obtained by dissolving 0.1 part of [3, (3,5-di-third-butyl-4-hydroxyphenyl) propionate] (manufactured by KOYO Chemical Research Institute, product name "Songnox1010") Share and make Dissolve.

Subsequently, the above solution was filtered using a metal fiber filter (manufactured by NICHIDAI, pore diameter of 0.4 μm) to remove minute solid components, and then a cylindrical concentrator dryer (manufactured by Hitachi, Ltd., product name "KONTRO") was used and At a temperature of 260 ° C and a pressure of 0.001 MPa or less, cyclohexane, xylene and other volatile components of the solvent were removed from the solution. The molten polymer was continuously filtered using a polymer filter (manufactured by Fuji Filter Co., Ltd.) having a sintered filter made of stainless steel having a pore size of 5 μm connected to a concentrating dryer, and the molten polymer was filtered from a mold at a temperature of 260 ° C. After the strand was extruded and cooled, 95 parts of pellets of the block copolymer hydride [2] -1 were prepared using a granulator. The weight average molecular weight (Mw) of the obtained pelletized block copolymer hydride [2] -1 was 80,200, and the molecular weight distribution (Mw / Mn) was 1.04. The hydrogenation rate was approximately 100%, and the glass transition temperature (Tg) was 143 ° C.

[Reference Example 2]

Except the block copolymer hydride [2] -2 (synthesis of block copolymer [1] -2) 20.0 parts of styrene, 20.0 parts of isoprene, 20.0 parts of styrene, 20.0 parts of isoprene and Except for 20.0 parts of styrene, each of which was divided into 5 times and added in this order, polymerization and reaction were stopped in the same manner as in Reference Example 1. The weight average molecular weight (Mw) of the obtained block copolymer [1] -2 was 79,100, the molecular weight distribution (Mw / Mn) was 1.04, and wA: wB = 60: 40.

(Synthesis of block copolymer hydride [2] -2)

Next, the above polymer solution was subjected to a hydrogenation reaction in the same manner as in Reference Example 1. The weight average molecular weight (Mw) of the hydrogenated block copolymer [2] -2 after the hydrogenation reaction was 79,900, and the molecular weight distribution (Mw / Mn) was 1.06.

After the hydrogenation reaction was completed, an antioxidant was added in the same manner as in Reference Example 1, and then concentrated and dried to obtain 91 parts of pellets of a block copolymer hydride [2] -2. The weight average molecular weight (Mw) of the obtained pellet-like block copolymer hydride [2] -2 was 78,900, and the molecular weight distribution (Mw / Mn) was 1.06. The hydrogenation rate was approximately 100%, and the glass transition temperature was 135 ° C.

(Example 1)

The pellets of the block copolymer hydride [2] -1 obtained in Reference Example 1 were subjected to heat treatment at 80 ° C. for 4 hours using a hot-air dryer that circulated air. The heat-treated pellets were used within 1 hour using a 50 mm uniaxial extruder equipped with a leaf disc-shaped polymer filter (filtration accuracy of 10 μm), and the extruder having the extruder shown in Table 1 The T-shaped extrusion die 1 of the compression die lip A is melt-extruded at 260 ° C, so that the extruded sheet-like block copolymer hydride [2] -1 is passed through 3 cooling drums (250 mm in diameter, The tube temperature was 105 and the take-up speed was 0.35 m / s) and cooled to obtain an optical film 1 having a width of 600 mm. The evaluation results of the obtained optical film 1 are shown in Table 2.

(Amount of dissolved air in the block copolymer hydride [2] -1 pellet removed by heat treatment)

5.0126 g of pellets of the same block copolymer hydride [2] -1 as used in Example 1 were added to a fine scale and added to a glass test tube with a ground stopcock and a ground end joint. Connected to the Toppler pump through the ground joint, and degas the air in the test tube at 25 ° C for 25 seconds. The stopcock of the test tube was closed, and the test tube was heated at 80 ° C. for 4 hours in an oil bath under the same conditions as the heat treatment in Example 1 to dissolve the pellets in the block copolymer hydride [2] -1. Air emissions. The test tube was stored at 80 ° C, and the amount of air exhausted in the test tube was measured using a Toppler pump at 25 ° C and normal pressure. The measured air volume was 0.787 ml. The amount of residual air in the test tube when the empty test tube was degassed under the same degassing conditions was 0.01 ml or less, which was an amount that could be ignored. When the average molecular weight of the air was 28.8 and the amount of discharged air was calculated, it was 10.12 × 10 ^-4 g, which was 202 ppm based on the weight of the block copolymer hydride [2] -1 pellets.

(Example 2)

An optical film 2 was obtained in the same manner as in Example 1 except that a T-shaped extrusion die 2 having an extrusion die lip B shown in Table 1 was used as the extrusion die lip. The evaluation results of the obtained optical film 2 are shown in Table 2.

(Example 3)

In addition to using the pellets of the block copolymer hydride [2] -2 obtained in Reference Example 2 and heat-treating at 80 ° C. for 5 hours, a T-shape having an extrusion die lip B shown in Table 1 was used. Except that the extrusion die 2 was used as the extrusion die lip, it was carried out in the same manner as in Example 1 to obtain an optical film 3. The evaluation results of the obtained optical film 3 are shown in Table 2.

(Example 4)

In addition to using the pellets of the block copolymer hydride [2] -2 obtained in Reference Example 2 and heat-treating at 60 ° C. for 5 hours, a T-shape having an extrusion die lip B shown in Table 1 was used. Except that the extrusion die 2 was used as the extrusion die lip, it was carried out in the same manner as in Example 1 to obtain an optical film 4. The evaluation results of the obtained optical film 4 are shown in Table 2.

(Comparative example 1)

Except that the T-shaped extrusion die 3 having the extrusion die lip C shown in Table 1 was used as the extrusion die lip, it was obtained in the same manner as in Example 1. Optical film 5. The evaluation results of the obtained optical film 5 are shown in Table 2.

(Comparative example 2)

An optical film 6 was obtained in the same manner as in Example 1 except that a T-shaped extrusion die 4 having an extrusion die lip D shown in Table 1 was used as the extrusion die lip. The evaluation results of the obtained optical film 6 are shown in Table 2.

(Comparative example 3)

Except that the pellets of the block copolymer hydride [2] -1 were used without heat treatment, and the T-shaped extrusion die 2 having the extrusion die lip B shown in Table 1 was used as the extrusion die lip Except this, it carried out similarly to Example 1, and obtained the optical film 7. The evaluation results of the obtained optical film 7 are shown in Table 2.

(Comparative Example 4)

In addition to setting the heat treatment conditions of the pellets of the block copolymer hydride [2] -1 to 40 ° C. for 4 hours, a T-shaped extrusion die 2 having an extrusion die lip B shown in Table 1 was used. Except for the die lip, the same procedure as in Example 1 was performed to obtain an optical film 8. The evaluation results of the obtained optical film 8 are shown in Table 2.

(Comparative example 5)

In addition to setting the heat treatment conditions of the pellets of the block copolymer hydride [2] -1 to 85 ° C. for 1 hour, a T-shaped extrusion die 2 having an extrusion die lip B shown in Table 1 was used. Except for the die lip, the same procedure as in Example 1 was performed to obtain an optical film 9. The evaluation results of the obtained optical film 9 are shown in Table 2.

(Example 5)

In addition to using the T-shaped extrusion die 2 with the extrusion die lip B shown in Table 1 as the extrusion die lip, the extrusion speed is increased, and the temperature of the cooling drum is changed to 95 ° C, and the winding speed is increased. Except changing to 0.41 m / s, it carried out similarly to Example 1, and obtained the optical film 10. The evaluation results of the obtained optical film 10 are shown in Table 2.

(Example 6)

In addition to using the T-shaped extrusion die 2 with the extrusion die lip B shown in Table 1 as the extrusion die lip, the extrusion speed was increased, and the temperature of the cooling drum was changed to 85 ° C., and the winding speed Except changing to 0.48 m / s, it carried out similarly to Example 1, and the optical film 11 was obtained. The evaluation results of the obtained optical film 11 are shown in Table 2.

(Example 7)

In addition to heating the pellets of the block copolymer hydride [2] -1 at 100 ° C. for 2.5 hours, and using a T-shaped extrusion die 2 having an extrusion die lip B as shown in Table 1 as the extrusion Except for the die lip, the same procedure as in Example 1 was performed to obtain an optical film 12. The evaluation results of the obtained optical film 12 are shown in Table 2.

(Example 8)

In addition to heating the pellets of the block copolymer hydride [2] -1 at 55 ° C for 2.5 hours, and using a T-shaped extrusion die 2 having an extrusion die lip B shown in Table 1 as the extrusion Except for the die lip, the same procedure as in Example 1 was performed to obtain an optical film 13. The evaluation results of the obtained optical film 13 are shown in Table 2.

[Table 1]

From the results of this example and comparative example, the following matters are known. The optical film of the present invention is as shown in the examples, and the height of the die line from the apex of the adjacent mountain to the bottom of the valley is 100 nm or less and the slope is 300 nm / mm or less. Therefore, when this film is extended and a polarizing plate is sandwiched to measure light leakage, even if a backlight plate with illuminance of 5,000 lux and 10,000 lux is used, no light leakage occurs (Examples 1 to 8).

On the other hand, in the optical film of the comparative example, the height of the die line from the apex of the adjacent mountain to the bottom of the valley was greater than 100 nm, and / or the tilt was greater than 30.0 nm / mm. Therefore, when this film is extended and polarized to measure light leakage, both 5,000 lux and 10,000 lux backlight panels are used. There was light leakage (Comparative Examples 3 and 4), and although there was no light leakage when using a backlight of 5,000 lux, there was light leakage when using a backlight of 10,000 lux (Comparative Examples 1, 2, 5).

When the average value of the surface roughness Ra of the extrusion die lip and the distribution range of the surface roughness Ra of the entire width of the extrusion die lip are larger than the range of the present invention (Comparative Example 1, Comparative Example 2), the die line The height and the inclination of the die line are larger than the scope of the present invention.

When the heat treatment conditions before melt extrusion of the pellets of the block copolymer hydride [2] are below the range of the present invention (Comparative Examples 3 to 5), the height of the die line is higher than that of the present invention. Large range, when using 5,000 lux and 10,000 lux backlight panels, light leakage occurs.

Industrial availability

The optical film system composed of the block copolymer hydride of the present invention has a small surface defect and has an excellent planar shape, and is useful as an optical film system such as a polarizer protective film, a retardation film, and the like. .

Claims (4)

An optical film comprising an optical film composed of a hydrogenated block copolymer [2] obtained by hydrogenating more than 90% of all unsaturated bonds of the block copolymer [1], and the block copolymerization The substance [1] is a polymer block [A] having at least two kinds of repeating units derived from an aromatic vinyl compound as a main component and a repeating unit derived from a chain conjugated diene compound as a main component. It is composed of at least one kind of polymer block [B], and the weight fraction of all polymer blocks [A] in the entire block copolymer is set to wA, and all polymer blocks [B] are in the block. When the weight fraction occupied by the entire copolymer is set to wB, the ratio of wA to wB (wA: wB) is 40:60 to 80:20, which is characterized in that the surface roughness of the lip of the extrusion die is used The average value of Ra is 0.05 μm or less, and the surface roughness Ra in the entire width of the lip of the extrusion die is distributed in an extrusion die of ± 0.025 μm or less of the aforementioned average value. The height from the apex of the adjacent mountain of the die line to the bottom of the valley is 100nm or less across the entire surface of the diaphragm. The inclination of the line system of the die surface of the diaphragm in the diaphragm full of 300nm / mm or less. [Number 1] Slope (nm / mm) = (height from the apex of the adjacent mountain to the bottom of the valley) / (width from the apex of the adjacent mountain to the bottom of the valley). ． ． Formula 1 A polarizing plate protective film includes the optical film described in item 1 of the scope of patent application. A retardation film is formed by extending an optical film as described in item 1 of the scope of patent application. An optical film manufacturing method comprising extruding a block copolymer hydride [2] by an extruder, extruding the extruding die attached to the extruder into a sheet shape, and extruding the extruder. The manufactured sheet-like block copolymer hydride [2] is formed by being closely adhered to at least one cooling drum, and the step of winding is characterized in that the average value of the surface roughness Ra of the lips of the extrusion die is 0.05. Extrusion molds with a surface roughness Ra of less than μm and the full width of the lip of the extrusion die are within ± 0.025 μm of the aforementioned average value, and are used for block copolymerization at a temperature of 50 to 120 ° C for more than 2 hours Pellets of hydride [2].